100V Line speaker systems are sometimes referred to as “constant-voltage system” it is the most economical way to install a multi-speaker sound system. The term 100V system relates to the maximum output voltage of the amplifier. To generate this high voltage the amplifier is equipped with a step-up transformer, which increases the normal output voltage of around 30 Volts, up to 100 Volts
The main difference between a low-impedance speaker system (4 or 8 Ohms) is the way the individual loudspeakers are connected to the amplifier, with the conventional low-impedance system special care has to be taken to maintain the correct impedance for the amplifier.
In a 100V line system, a large number of single loudspeakers each equipped with a step-down transformer can be connected to one single speaker cable. With the 100V line installation, each speaker or speaker cabinet is equipped with a step-down transformer
A step-down transformer has relatively high impedance at the primary side and the secondary side of the transformer matches the speaker impedance (typically 8 Ohms). The primary side of the transformer normally has several tapping’s, these are marked in watts and are used to enable each speaker to be set at different volume levels. The total primary wattage should not exceed 90% of the amplifiers output. A step-down transformer will be required for each loudspeaker cabinet connected to the amplifier.